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Assessment of fetal atrioventricular time intervals by tissue Doppler and pulse Doppler echocardiography: normal values and correlation with fetal electrocardiography
  1. M Nii1,
  2. R M Hamilton1,
  3. L Fenwick1,
  4. J C P Kingdom2,
  5. K S Roman1,
  6. E T Jaeggi1
  1. 1Division of Cardiology, The Hospital for Sick Children, Toronto, Ontario, Canada
  2. 2Division of Maternal-Fetal Medicine, Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada
  1. Correspondence to:
    Dr Edgar T Jaeggi
    Fetal Cardiac Program, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada; edgar.jaeggi{at}


Objective: To establish gestational age-specific reference values of normal fetal atrioventricular (AV) time interval by spectral tissue Doppler imaging (TDI) and pulse-wave Doppler (PD) methods, and to assess their correlation with signal-averaged fetal PR intervals (ECG).

Design: Cohort study.

Setting: Tertiary centre for fetal cardiology.

Patients and measures: 131 pregnant women between 14 and 42 weeks’ gestation underwent 196 fetal echocardiograms and 158 fetal ECG studies. TDI-derived AV intervals were measured as the intervals from atrial contraction (Aa) to isovolumic contraction (IV) and from Aa to ventricular systole (Sa) at the right ventricular free wall. PD-derived AV intervals were measured from simultaneous left ventricular inflow/outflow (in/out) and superior vena cava/aorta (V/AO) recordings.

Results: Measurements were possible by ECG in 61%, by TDI in 100%, by in/out in 100% and by V/AO in 97% of examinations. Aa-IV correlated significantly better with PR intervals (y  =  0.67x + 38.29, R2 =  0.15, p < 0.0001, mean bias 8.0 ms) than did in/out (R2  =  0.10, p  =  0.002, bias 18.7 ms) and V/AO (R2  =  0.06, p  =  0.02, bias 12.4 ms). Gestational age and AV intervals were positively correlated with all imaging modalities (R2  =  0.19–0.31, p < 0.0001).

Conclusion: This study showed the feasibility of fetal AV interval measurements by TDI, and established gestational age-specific reference data. TDI-derived Aa-IV intervals track ECG PR intervals more closely than PD-derived AV intervals and thus should be used as the ultrasound method of choice in assessing fetal AV conduction.

  • Aa, atrial contraction
  • AV, atrioventricular
  • in/out, inflow/outflow
  • FEMO, fetal ECG monitor
  • IV, isovolumic contraction
  • PD, pulse-wave Doppler
  • Sa, ventricular systole
  • TDI, tissue Doppler imaging
  • V/AO, superior vena cava/aorta

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  • Published Online First 14 June 2006

  • This study was supported by a seed grant from The Hospital for Sick Children, Toronto and a grant from the Heart and Stroke Foundation of Ontario.

  • Competing interests: None declared.

  • The study was approved by the Research Ethics Board of The Hospital for Sick Children, and written informed consent was obtained from each participating woman.